Rigid Container and Inner Bag Structure for Fast Detachment
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Solution Overview
Problem
Existing methods for producing containers with a rigid outer container and deformable inner bag result in adhesion between the two materials, requiring elaborate detachment processes that increase production time.
Innovation Solution
The inner bag's outer layer is composed of a thermoplastic material with a rough surface of microscopically small elevations and depressions, formed by mixing EVOH with Surlyn and optionally glass beads, ensuring minimal adhesive forces with the outer container, and the pinch-off seam is partially opened to facilitate easy detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the inner bag is made with a smooth surface material, then the adhesion between inner bag and outer container increases, but the detachment process becomes more difficult and time-consuming
Solution Approach 1:
The invention changes the surface parameter of the inner bag material from smooth to rough. The outer layer (2) is formed with a rough surface having microscopically small elevations and depressions, which reduces the contact area and adhesive forces between the inner bag and outer container, enabling easy detachment without increasing production time
Solution Approach 2:
The invention uses a composite material structure for the inner bag with at least three layers. The outer layer (2) consists of a thermoplastic material with rough surface properties, while inner layers provide structural integrity. This composite structure combines the benefits of adhesion during production with easy detachment after production
2Loss of time
If the inner bag is made with a rough surface material, then the adhesion between inner bag and outer container decreases, but the detachment process becomes easier and faster
Solution Approach 1:
The invention optimizes the surface roughness parameter of the inner bag's outer layer to achieve minimal adhesive forces. The microscopically small elevations and depressions create a surface that allows rapid detachment while maintaining sufficient adhesion during the production process to prevent defects
3Reliability
If pressure-equalising holes are provided in the outer container wall, then the pressure equalisation during filling is improved, but the structural integrity and cleanliness of the container is compromised
Solution Approach 1:
The invention removes the pressure-equalising holes from the outer container wall design. Instead, pressure equalisation is achieved through the detachable nature of the inner bag, which can be easily separated from the outer container to equalize pressure during filling without compromising the container's structural integrity or cleanliness
Solution Approach 2:
The inner bag acts as an intermediary element that facilitates pressure equalisation. By detaching the inner bag from the outer container, pressure can be equalized during filling without creating holes in the outer container wall, thus maintaining structural integrity and cleanliness
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design allows for quick and easy detachment of the inner bag from the outer container, reducing production time and maintaining minimal adhesion during use.
Implementation Method 1
The second thermoplastic plastics material which forms the outer layer of the inner bag (2) and which, in the hardened state, has a rough surface having microscopically small elevations and depressions, so that the adhesive forces between the outer container (1) and the inner bag (2) are minimal.
Data Source
AI summary
The method for producing a container consisting of a rigid outer container and a deformable inner bag. A first screw conveyor supplies a first thermoplastic plastics material for the outer container and at least a second and a third screw conveyor supplies at least a second and a third thermoplastic plastics material for the inner bag to an extruder which coextrudes a parison consisting of at least the first, second and third layers. The parison is inflated by a pressure medium to bring it into contact with the wall of the blow mould, where excess material below the welded seam is cut off and the container is removed from the blow mould. The second thermoplastic plastics material forming the outer layer of the inner bag consists of a material which, in the hardened state, has a rough surface having microscopically small elevations and depressions.